By grace



F. H. MERRILL. DECD. G. E. MERRILL. ADMINISTRATRIX FIRE SCREEN FOR tXPLOSIVE enemas.

APPLICATION FILED HAY I4. l9l7.

Patented oat. 7,1919.

//VVE/Y 727/? 1 .72 MerrM/a-aeasea racc E Nerd/401171 I 60 5) #512 ATTOP/YEK? rr/r/vfasfs Z' 60M a 9/ W W UTE s Tns PATN OFFIQE.

FRANK I-I. MERRILL, DECEASED, LATE OF HENNEPIN COUNTY, MINNESOTA, BY' GRACE E. MERRILL, ADMINISTRATRIX, OF MINNEAPOLIS, MINNESOTA, ASSIGNOR TO VEERAC COMPANY, OF MINNEAPOLIS, MINNESOTA, A CORPORATION OF MINNESOTA.

FIRE-SCREEN FOR EXPLOSIVE-ENGINES.

I To all whom it may concern:

Be it known that FRANK deceased, late citizen of the United States, and

resident of the county of Hennepin and State of Minnesota, had invented certain new and useful Improvements in Fire- Screens for Explosive-Engines; that GRACE E. MERRILL, widow of the said FnANK E. MERRILL, has been duly appointed administratrix of the estate of said FRANK H; MER- RILL, and that'the said-GRACE E. MERRILL, administratrix, does hereby declare the following to be a full, clear, and exact description of the invention, such as willenable others skilled in the art to which it appertains to make and use the same.

This invention relates to explosive engines and provides an improved form of fire screen *for preventing back-firing of the charge into the crank shaft compression chamber of an explosive engine.

Generally stated, the invention consists of the novel devices and combinations of devices hereinafter defined and described in the claim.

In the accompanying drawings, which illustrate the invention, like characters indicate like parts throughout the several views. I

Referring to the drawings: 7

Figure 1 is a plan viewwith some parts broken away, showing the improved fire screen applied in the transfer passage of an explosive engine of the two cycle type; I

Fig. 2 is a vertical section on the line 22 of Fig. 1; and 1 Fig. 3 is a plan view with some parts sectioned, showing the improved fire screen in detail.

Of the parts of the explosive engine, it is only necessary for the purpose of. this case to particularly note the cylinder 4 and the crank shaft compression chamber 5 into which the inner end of the cylinder directly opens. The cylinder has a fuel admission port 6 and an exhaust port 7, and it is connected to the crank shaft compression chamher at its intermediate portionby a transfer Specification of Letters Patent.

The improvedfire screen, shown in detail in Fig. 3, is made up of amultiplicity of laterally spaced thin metal washers 12 and interposed relatively small spacing washers 12*, the entire stack being held together in cylindrical form by a clamping bolt 14 provided with a nut 15.

In some instances, the cylindrical screen .Wlll be lnterposed directly in a seat formed has a shaft or stem at one end that is equipped with an operating lever 18 that may be directly operated or connected to an extended operating connection, not shown.

When the valve 16 is in its open position, shown in Fig. 2, the screen will operate just as if it were inserted directly into a cylindrical seat *formed in the said transfer passage, and, in fact, it'is then in effect so seated. 7

It is a well known fact that a fire screen prevents flames from passing through the same, by rapid radiation of the heat which reduces the flame below the flashing point of most gases. In this improved screen the plurality of metal washers serve to rapidly conduct the heat, as well as to break up the flame, and thus to prevent the flame from igniting gas that is within the crank shaftcompression chamber or in the transfer port 8 between said compression chamber and screen.

When the valve isin an open position, the" interior thereof and the ports therein constitute an expanded chamber in the transfer port in which the fire is interposed. The spacing washers being of much less diameter than the heat conducting washers, or disks, constitute a core which divides the hot gases into two streams and causes the two streams to pass between difi'erent portions of said plates. This produces the greatest possible efliciency in the fire screen with a minimum of obstruction to the passage of the gases. The two streams divided 7 PatentedOctfl, 1919. Application filed May'14, 1917. Serial No. 168,467. i i

by the core are,iof course, each sub-divided into a inllltlPllCltyhOf streams-in passing between the conducting plates.

Itis alsoimpor-tant-to note; that the disk- -llike conductingplates of the fire screen, avhenyplaoedwvithin the hollow valve-have direct contact with the interior of said valve at its peripheral edgesso thatthere will be a good conduction of heat, first, t0 the said valve and froin,.tlie11ce, to the cylinder casting.

It Wlll removed thefire screen, as an ent1rety, may

*be" 'lHlOVECl fre11rthe-ya1ve 1 and may be eleanclrandremeerted-,-w-1thout disturbi *01: remevmg tl16*Vtl-VG. On-the {other hand,

- tvhentheplug 4 -is-removed,the valve, to-

get-her: WitlYtlie fiIe screen there-im-may be removed from the valve seat.

These funct1ons,,as 1s, obvious, are -1n1portant1n the operation-of; an-engine. Where a firing screen may-require frequent cleanln --inoved thepl-ugbe brought *t-herewith- *out of w'-orking' position. 7

, In actual 1 practice, the above *file screen h-as- -been{ foiind highly eflicient for the gurposesyhad in view. In iact,--it has 'een be noted that when the plug L is foundinuch more eiiicient than an ordinary .Woven avire screen.

transfer passagethat includes a sleeve-like valve seat, of a hollow cyllndrical valve seatedlin said transfer passage'and having lateral ports, a fire screen detachably seated in said val-ve,= i-ndependently removable plugs closing the ends of said valve seat, said valve l1av1ng an operatlng stemextended through-,ene of said plugs, thatend ofthe cavity of said valve" that is adjacentto the lolaposite p1 ug -beingopen for the r-e'nioval or said-screen from said-valve, when said latter noted plug is removed,

a In testimony whereof 1" any fisignatu re' the presence of two witi lessesa emcee. MERRILL,

Admim'stmta im r of Frank H. -Meh ill, (le

ceased.

Witnesses: I V

CLARA DEMAREST, Di 'MERGHANT. 

